Thermal reactor with relatively movable internal pipe sections

ABSTRACT

A thermal reaction pipe system for use with exhaust pipes of internal combustion engines or the like where hot gases flow through a series of divided internal pipe sections which are thermally insulated from an external pipe section, the internal pipe sections being slidable relative to each other to relieve stresses in the pipe system caused by heat expansion as well as differing thermal expansion coefficients between internal and external parts.

United States Patent [191 Kern [4 1 Feb. 11, 1975 I 1 THERMAL REACTOR WITH REL ATIVELY MOVABLE INTERNAL PIPE SECTIONS [75] Inventor: fler hert lfiern,Altensteig,

Germany [73] Assignee: Firma Friedrich Boysen, Black Forrest, Stuttgart-Heumaden, Germany 22 Filed: July 26,1972

2] Appl. No.: 275,336

[30] Foreign Application Priority Data July 28, 1971 Germany 2137699 Jan. 8, 1972 Germany 2200815 [52] US. Cl 60/282, 60/320, 60/322, 60/323, 285/41, 285/53 [51] Int. Cl. F0ln 7/10 [58] Field of Search 60/282, 320, 272, 322,

[56] References Cited UNITED STATES PATENTS 881,378 3/1908 Cowles 285/331 1,295,295 2/1919 Flagge....

Fogas 23/277 C 2,759,491 8/1956 Everhart 285/331 3,460,916 8/1969 3,470,690 10/ l 969 3,488,723 1/1970 Veazie 3,645,092 2/1972 Tatsutomi et al 3,666,422 5/1972 Rossel 23/277 C 3,683,625 8/1972 MCCrink..... 3,727.410 4/1973 Scheitlin 60/282 X FOREIGN PATENTS OR APPLICATIONS 76,109 8/1954 Netherlands 60/323 914,489 6/1946 France 285/47 Primary Examiner-William L. Freeh Assistant Examiner-Robert E. Garrett [57] ABSTRACT A thermal reaction pipe system for use with exhaust pipes of internal combustion engines or the like where hot gases flow through a series of divided internal pipe sections which are thermally insulated from an external pipe section, the internal pipe sections being slidable relative to each other to relieve stresses in the pipe system caused by heat expansion as well as differing thermal expansion coefficients between internal and external parts.

17 Claims, 19 Drawing Figures THERMAL REACTOR WITH RELATIVELY MOVABLE INTERNAL PIPE SECTIONS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to thermal reactors for use in exhaust pipes of internal combustion engines wherein the combustible substances in exhaust gases are permitted to complete combustion thereby reducing the harmful substances of the exhaust emission from the engine.

2. Description of the Prior Art In the pipe system comprising a thermal reactor it is required that, due to the exceptionally high temperatures maintained in the reactor, that the inner parts of the reactor be appropriately insulated from the external parts in order that the inner parts may reach and maintain the high temperatures required.

In view of the high temperatures existing in the pipe assembly, very high stresses may occur between the internal and external parts of these pipes in view of different thermal expansion of the parts during operation of the reactor. Consequently, such expansion and con traction differences eventually result in cracking or leaking of the pipes with the reactor having to be replaced. The expansion differences are even further increased if the materials making up the internal parts have different thermal expansion coefficients from the materials making up the external part, this being the usual situation as preferably the internal parts are made out of heat-resisting metallic alloys, such as nickel alloys which have a high thermal expansion coefficient, while for economical reasons a lower grade and less expensive material is used for the external parts, such material having a lower thermal expansion coefficient.

To cope with the different thermal expansions, it is known to connect the external parts with the internal pipe at only one position and support it in a sliding manner in other areas to permit for the heat expansion. However, this design has the significant disadvantage that mechanical forces introduced externally of the reactor, such as tensile, compression or bending stresses, are directly transmitted to the hot internal pipe portions which the slidingly supported external sleeve portions are only insignificantly stressed. These forces and stresses are a severe disadvantage as the strength of the pipe system of the reactor is significantly reduced with increasing temperatures thereby significantly reducing the useful life of the reactor.

SUMMARY OF THE INVENTION The present invention overcomes the problems and disadvantages of the known type of thermal reactor pipe assemblies by providing an internal pipe which is subdivided into sections which slide into or over each other with the forces and stresses exerted thereon being carried by the external sleeve section surrounding the internal pipe section. Thus, the extremely hot internal pipe sections can slide relatively to each other and will not be subjected to the physical stresses previously encountered by prior art devices as the external sleeve section acts as a supporting member and serves to transfer the forces and stresses from one end of the thermal reactor to the other without affecting the internal pipe sections of the same. Thus, the mechanical stresses of the divided internal pipe section are relieved with the external sleeve transmitting all such forces and stresses in a manner bypassing the internal pipe section of the reactor.

A further advantage of the present invention is that the internal pipe sections may have thin walls as they will not be stressed mechanically, thus the expensive heat resistant material required for these internal parts can be reduced to a minimum resulting in a substantial cost saving. Further, by providing thin pipe walls the reduced mass and reduced heat capacity of the thin walled internal parts will initiate a reaction more quickly to oxidize and burn up the combustibles in the hot exhaust gases than if thick pipe walls were provided.

Still a further advantage is that the present invention permits the use of different materials for internal and external pipes having different thermal expansion coefficients so that while the internal pipe is made of expensive heat-resistant material, the external pipe may be manufactured from a less expensive lower grade material being resistant to scaling. When using this low grade material, caps are attached at opposite ends for spacing the material. from the internal pipes while simultaneously joining the opposite ends of the external sleeve to the entrance and exist ends of the reactor, such sleeves preferably being of a high grade heat and scale resistant material.

Still a further provision of the present invention is to provide for a sliding seal between neighboring internal pipe sections where the internal pipe section positioned up-stream of the direction of gas flow through the reactor is slidingly supported by the neighboring internal pipe section positioned down-stream of the gas flow. This provides ajoint where the gas must first reverse its flow of direction before it can pass through the joint.

A further advantage is to provide insulating material enclosing the internal pipe sections at least in the area where the sections overlap in a manner sealingly bordering the overlapping joint sections posing a resistance against any outflowing gas from the joints.

Yet a further advantage of the invention is to provide an insulating material between the inner and external pipe sections with the layer of insulation material nearest the hot internal pipes having a high density with the layer of material nearest the external pipes having a lower density to assist in the sealing of the joints between the hot pipe sections and preventing gas leakage through the joints from penetrating into the insulation.

Yet a further advantage of the present invention is to provide for the sliding relative movement of the internal pipe sections into or on each other in a substantially airtight manner by use of a slide sealing ring working in a fashion similar to a piston ring of an engine so that sliding of the internal pipe sections can occur with an airtight seal being maintained therebetween at the point of sliding contact.

Yet a further advantage of the present invention provides a joint seal of a non-airtight sliding manner which provides for a labyrinth-type path which any leakage gas must pass thereby substantially reducing any leakage along with reducing the force of gas flow in view of the changes of gas direction required to penetrate the labyrinth path such that there is no physical destruction of the surrounding insulation due to the force of the leakage gas.

A still further advantage of the invention is to provide a pressure equalization chamber between the internal and external pipes equalizing the pressure or vacuum formed between the sliding joints and the insulation chamber.

A further advantage of the invention provides for insulating material between the internal and external pipes with the insulating material in the areas of the joints between the internal pipes being of a gas resistant material to resist any gas leaking through the joints.

Other features and advantages of the invention will be apparent during the course of the following description of preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings forming a part of this specification, and in which like reference characters are employed to designate like parts throughout the same:

FIG. 1 is a fragmentary view in vertical section taken along the longitudinal axis of the reactor illustrating a first embodiment of the invention;

FIG. 2 is a fragmentary sectional view similar to FIG. 1 and illustrating a further embodiment of the invention;

FIG. 3 is a fragmentary sectional view similar to FIG. 2 and illustrating a further embodiment of the invention;

FIG. 4 is a fragmentary sectional view similar to FIG. 2 illustrating a further embodiment of the invention;

FIG. 5 is a fragmentary sectional view similar to FIG. 2 and illustrating a further embodiment of the invention;

FIG. 6 is a view in vertical section illustrating an S- shaped further embodiment of the invention;

FIG. 7 is a view in vertical section of a nonsymmetrical embodiment of the invention;

FIG. 8 is a fragmentary sectional view illustrating an alternative way of connecting a mounting flange to the reactor of FIG. 7;

FIG. 9 is a fragmentary broken-away view in vertical section of a further embodiment of the invention with branch pipes attached to the internal pipe section;

FIG. 10 is a fragmentary view in vertical section of a further embodiment of the invention showing a longitudinally divided internal pipe and branch pipes attached thereto;

FIG. 11 is a sectional view taken along Line 11l1 of FIG. 10;

FIG. 12 is a fragmentary top view of a portion of FIG. 10;

FIG. 13 is a fragmentary broken away sectional view similar to FIG. 11 and illustrating a variation thereof;

FIG. 14 is a fragmentary view in vertical section illustrating a sliding joint connection between internal pipe sections;

FIG. 15 is a side elevational view, partially broken away and partially in section, of a further embodiment of the invention utilizing an airtight sliding seal between internal pipe sections;

FIG. 16 is a fragmentary top plan view of a portion of FIG. 15;

FIG. 17 is a sectional view taken on line 17-17 of FIG. 15;

FIG. 18 is a side elevational view in vertical section of a further embodiment of the invention showing internal branch pipe sections and a sliding non-airtight joint between internal pipe sections; and

FIG. 19 is a view in partial section taken on line 1919 of FIG. 18.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. 1, there is shown a pipe system consisting of three internal pipe sections 20, 21 and 22, and an external sleeve 23. The internal pipe sections are identified as terminal end section 20, center section 21, and end section 22. The external sleeve 23 may be designed as a single piece section, but preferably consists of a middle section made out of relatively plain and inexpensive material having two end caps 24 and 25 welded to the opposite end of the middle section with cap 24 engaging the outer'wall surface 20a of end pipe section 20 and cap 25 engaging outer wall surface 22a of end pipe section 22. The caps 24 and 25 are preferably manufactured out of a relatively expensive and scale resistant material. The caps 24 and 25 are each welded in an airtight manner to the outer surfaces 20a and 22a of the pipe sections 20 and 22 as shown at positions 24a and 25a in FIG. 1 providing an airtight pipe system interconnecting terminal end pipe sections 20 and 22.

The pipe sections 20, 21 and 22 are longitudinally axially aligned with each other. One end of pipe 20 is slidingly received within the adjacent expanded end 28 of pipe 21 with a spacing 26 between the end of pipe section 20 and the unexpanded interior end of pipe section 21. The opposite end of pipe section 21 is slidingly received within expanded adjacent end 29 of pipe section 22 with a spacing 27 between the end of section 21 and the interior non-expanded end of section 22. A spacing 30 is present between the exterior wall surface 200 of section 20 and the interior wall surface of end 28 of section 21, with a spacing 31 between exterior wall surface 21a of section 21 and the interior wall surface of end 29 of section 22. In this manner a slide joint is formed between sections 20 and 21 with a further slide joint being formed between sections 21 and 22. The spacings 30 and 31 of these slide joints are just sufficient to provide for the required sliding of the adjacent pipe sections on or in each other. Further, the selection of which section is inserted into which section is chosen such that the direction of gas flow through the sections, indicated generally by arrow X, is such that the gas flowing therethrough would have to reverse its direction of flow if it were to penetrate through the gaps 26 and 27 along the clearances 30 and 31 to leak out of the pipe sections.

The cavity defined between the external wall surfaces of internal pipe sections 20, 21 and 22 and the internal wall surface of external sleeve 23 is filled with an insulating material 32. The insulating material provides a thermal insulation between the external and internal pipe section and may be ofa material of higher or lower insulating density, and may include therein aluminum, silicon, or the like. The insulating material is preferably evenly distributed through the cavity in such a manner that it assists in sealing and preventing gas leakage through clearances 30 and 31 while at the same time not restricting the sliding motion between the internal pipe sections 20, 21 and 22 when they expand and contract under the influence of the hot gas flowing therethrough.

Referring to FIGS. 2 through 5, there are illustrated further embodiments of the invention which are similar to the embodiment of FIG. 1, and due to such-similarity and in order to avoid needless repetition of description, like reference numerals have been assigned to identify like and corresponding parts between the disclosures of FIG. 1 through FIG. 5.

Referring to the embodiment of FIG. 2, this is similar to the embodiment of FIG. 1 except the insulating material 32 filling the cavity defined between internal pipe sections 20, 21, 22 and external sleeves 23 is of a layered material having an inner layer 32a of higher density surrounding the internal hot pipe sections with the outer layer 32b being of lower density and filling the remainder portion of the cavity. It is preferred that the insulating material be elastic so that it can yield to heat expansion of the wall surfaces of the internal pipe sections. However, if insulating material is used which is not elastic, then it is preferred that a slight clearance exists between the insulating material and the walls of the pipe section in a cold condition so that in a hot condition the insulating material is resting tightly against the heat expanded wall surfaces of the internal pipe sections.

The embodiment of FIG. 3 is similar to FIG. 1 except that the cavity between external sleeve 23 and internal pipe sections 20, 21, 22 is filled with an insulating material 32a of high density in juxtaposition to the sliding joints between sections and 21 and sections 21 and 22 respectively to assist in the sealing of the clearances 30 and 31 to assist in preventing leakage of gas therethrough. The remainder of the cavity being filled with an insulating material 32b of lower density.

The embodiment of FIG. 4 is similar to the embodiment of FIG. 3 except that the segment of insulating material 32a associated with clearances 30 and 31 respectively extend completely between the sleeve 23 and internal pipe sections 20, 21', 22 with the remainder of the cavity being filled with the insulating material 32b of lower density.

The embodiment of FIG. 5 is similar to the embodiment of FIG. 1 with the cavity defined between external sleeve 23 and internal pipe sections 20, 21, 22 being of the same density throughout. However, there is additionally provided a mechanically strong and resistent insulating sheet or foil 33, such as a nickel alloy, which is interposed between the insulating material 32 and the hot wall surfaces 20a, 21a, 22a of internal pipe sections 20, 21, 22. The foil 33 is arranged in contacting juxtaposition with the wall surfaces 20a, 21a, 22a such that even if the insulating material 32 is barely loosely arranged in the cavity the foil will serve to prevent hot gases from leaking through clearances 30 and 31 and penetrating into the pores or spaces between the insulating material 32 and reaching the external sleeve 32 in a hot condition. In addition, the foil 33 may enclose the entire insulating material 32 in order to form an insulating package so that the entire package may be readily inserted into the cavity during assembly of the thermal reactor while protecting the insulating material against any damage in the handling of the same.

Referring to FIG. 6, there is shown a further embodiment similar to FIG. 1 where the thermal reactor has been bent to a general S-shape and includes external sleeve 123 and internal pipe sections 20, 121 and 22. The center pipe section 121 comprises the S-shaped portion of the system with the expansion gaps 26 and 27 between opposite ends of center pipe section 121 and terminal end pipe sections 20, 22 are each positioned in the transition of the curving pipe section 121 to the straight pipe sections 20, 22. The external sleeve 123 conforms in shape to the S-shape of the pipe section with a cavity defined between the internal wall surface of external sleeve 123 and the exterior wall surfaces of pipe sections 20, 21, 22, the cavity being filled with insulating material 32. By having the center pipe section 121 being of the S-shape and slidingly interconnecting end pipe sections 20, 22 with gap clearances 26 and 27 along with sliding clearances 30 and 31, compressing and bending of the internal pipe section is precluded upon expansion when heated. In principle, this applies not only to S-shaped pipe sections, but also for pipes bent to other semi-circular shapes. Further, it is to be understood that the embodiments explained previously regarding FIGS. 1 to 5 may equally be embodied in this embodiment of FIG. 6.

Referring now to FIG. 7, there is shown an embodiment consisting of a bellows-type system where internal pipes 220, 221 are each rigidly mounted at one end by flanges 233 to the housing of an internal combustion engine (not shown), the flanges 233 being welded to the ends of the internal pipe sections. The unmounted end of pipe section 220 is slidably received within the unmounted expanded end of pipe section 221 and spaced axially therefrom by gap 226 with radial sliding clearance gap 230 between the exterior wall surface 220a of section 220 and the interior wall surface 221a of pipe section 221.

External sleeve 223 is spaced from the internal pipe sections 220, 221 with the ends thereof welded in an airtight manner to flange 233 to define a cavity between external sleeve 223 and internal pipe sections 220, 221, with insulating material 232 being inserted into the cavity. This embodiment avoids stresses caused by varying heat expansion and provides mechanical relief to the internal portions of the bellows pipe from mechanical strain, transferring these loads and stresses to the external sleeve 223 which is designed mechanically strong and airtight.

Referring now to FIG. 8, there is disclosed an alternative embodiment to that of FIG. 7 as to the mounting of the internal pipes 220, 221 and the external sleeve 223 to the flange 233 and the mounting of the flange to the housing of an internal combustion engine (not shown). In order to avoid needless repetition, only the flange mounted end portion of internal pipe section 220 is shown, it being understood that the same type of flange structure is used with the flange mounted end of internal pipe section 221. In this form of the invention, the end of the internal pipe section 220 having wall surface 220a extends up to the face side of mounting flange 233 and is welded thereto. The flange mounted end of external sleeve 223 extends up to the mounting flange and is welded thereon. As before, the cavity between external sleeve 232 and the internal pipe section is filled with an insulating material 232. Holes 234 are located in flange member 233 externally of external sleeve 232 for receiving screws (not shown) for mounting the assembly rigidly to the housing of an internal combustion engine (not shown).

Referring to FIG. 9, a further modified form of the invention is disclosed having a plurality of internal pipe sections having branch pipes 337, 338 connected to center pipe sections 321, 321x respectively. Again, in order to avoid needless repetition of description, similar reference numerals but of a higher order have been applied to the corresponding parts as between the disclosures of FIG. 1 and this FIG. 9. In this latter form of the invention, the internal pipe sections are defined by reference numerals 320, 321, 321x and 322 with the external sleeve 323 extending thereover having the end shown in the drawings welded airtight to caps 325 which in turn is welded airtight to the wall surface 322a of terminal end pipe section 322 at point 325a. It is understood that the opposite end of sleeve 323 is similarly provided with a cap which is similarly welded airtight to terminal end pipe section 320. Axial clearance gaps 326, 327x and 327 along with circumferential sliding clearances 330, 331): and 331 are provided to form the sliding joints between sections 320 and 321, sections 321 and 321x, and sections 321x and 322. A branch pipe 337 is connected to center pipe 321 and extends perpendicular therefrom through the external sleeve 323, with a similar branch pipe 338 connected to center pipe section 321x and extending perpendicular therefrom through external sleeve 323, the branch pipes adapted for connection to the exhaust openings or pipes (not shown) of internal combustions engines. The cavity defined between the external sleeve 323 and the pipe sections 320, 321, 321x, 322, 337, and 338 being filled with insulating material 332.

In FIGS. 10 to 12 a further modified form of the invention is disclosed, and in order to avoid needless repetition of description similar reference numerals but of a still higher order have been applied to the corresponding part as between the disclosures of FIG. 9 and FIGS. 10-12. This latter form of the invention discloses an internal pipe having a longitudinal wall 439 partially extending axially therethrough separating the internal pipe into two channels 440 and 441. A branch pipe 438 has one end connected to channel 441 and extends outwardly therefrom through external sleeve 423 for connection to the exhaust ports of cylinders of internal combustion engines. A further branch 437 has one end slidably received in an expanded end portion of channel 441 and is axially spaced therefrom by axial gap 427x with circumferential sliding clearance 431x between the wall surface 441a of branch pipe 437 and the expanded portion of channel 441. The opposite end of branch pipe 437 is connected to the internal combustion engine in the same manner as branch pipe 438. It is understood that additional branch pipes, such as 440a, may be longitudinally spaced along channel 440 in the same manner as branch pipe 437 for interconnecting the channel to the exhaust of an internal combustion engine. Further, it is understood that as the longitudinal separating wall 439 only extends through a portion of the internal pipe, that channels 440 and 441 may be united as a single internal pipe prior to encountering the branch pipes.

The separating wall 439 is clamped between the two channel-shaped wall sections of the internal pipe. The internal wall connected to branch pipes 437 and 438 being divided into wall sections 441a, 441b and separated by axial expansion gaps 426, 427.1: and 427 from each other and terminal end pipe sections 420a and 422a. As previously described, each joint associated with said expansion gap also has circumferential sliding clearance gaps 430, 431x, 431.

Channel 440 may be similarly sub-divided as channel 441. As shown, there is provided a semi-circular shell 442 forming a pipe having an expanded end portion 428 overlapping the adjacent neighboring curved pipe section 440a having a wall surface 442a, with an axial expansion gap 426a formed therebetween. The separation wall 439 is positioned between flanges 443 and 444 of the semi-circular wall sections 441a, 442 and folded around the flange 443 at the side 445. The shell 442 is held is position by the insulating material 432 inserted in the cavity defined between the external sleeve 423 and the internal channels and pipe sections.

Referring to FIG. 13, there is shown a more rigid mounting for shell 442 by providing the insulating material 432 about the flanges 443, 444 be made out of a stronger and denser insulating material 432a while in other locations a looser or less dense insulating material 432b can be used.

Further, it is appreciated that the external sleeve 423 can be also assembled out of two shells 423a, 432b which are provided with flanges and welded in an airtight manner. It is understood that this may also be applied to all other embodiments of the invention, and that where applicable, the external sleeve may also consist of more than two shells welded together in an airtight manner.

Referring to FIG. 14, a further modified form of the invention is disclosed. In order to avoid needless repetition of description, only one end portion of the pipe assembly is shown with it being understood that the same may extend over a multiplicity of pipe sections depending upon the desired usage. Still further, similar reference numerals but of a still higher order have been applied to the corresponding parts as between the disclosure of FIG. 1 and this FIG. 14. In this form of the invention, one end of the internal center pipe section 521 is provided with concentric radially spaced apart pipe walls 521a, 52111 welded together at point 521e, thus providing an annular space for slidably receiving therein the adjacent end 522a of internal pipe section 522 with circumferential clearances 531a, 531b formed between pipe end 522a and pipe walls 521a, 5211;. A cavity 547 is formed between walls 521a, 521b adjacent point 521a and provides the axial spacing gap between pipes 521, 522. The external circumferential clearance 521b communicates on one side with cavity 547 and on the other side with a pressure equalization chamber 549 which is formed radially between end wall 522a and external sleeve 523. The physical size of the chamber is defined on one side by a wall 548 holding insulation 532 in the cavity defined between exter nal wall 523 and internal pipe sections 521, 522, and is limited on the other side by wall section 525 forming an airtight connection between the external sleeve 523 and internal pipe section 522.

Upon the passage of hot gases through internal pipes 521, 522 in the direction of arrow X, heat expands the internal pipe section 521 which, by means of concentric walls 521a, 521b expands along wall 522a. The circumferential joint clearances 531a, 531b create a type of labyrinth seal, with any gases succeeding in passing through the seal reaching the pressure equalization chamber 549 after changing direction of gas flow at least twice. The pressure equalization chamber equalizes pressure variations caused by the heated expansion of the pipes.

Referring now to FIGS. 15-18, there is disclosed two further embodiments of the principles of the present invention wherein the internal pipe is not divided in the reaction zone with pipe extending in the direction of the gas flow and the sliding joint between the pipe sec tion being positioned outside the hottest reaction area. The illustrations of FIGS. -17 illustrate one of the embodiments, and FIGS. 18-19 illustrate the other embodiments.

Referring now to FIGS. 15-17, there is shown a pipe system having an elbow member 610 which is adapted for direct or indirect mounting to the exhaust of a combustion engine (not shown). Reference numeral 61] generally indicates a pipe assembly having one end adjacent the elbow 610, the pipe 611 including an external sleeve 612 and an internal pipe 613, with internal pipe 613 including internal pipe sections 614 and 615. Internal pipe section 614 is formed by an airtight welding of pipe sections 614a and 614b at point 616. The internal pipe section 615 has one end 615a slidingly protruding within the adjacent end of internal pipe section 614, with the adjacent end of pipe section 614 having an expanded portion 614c for overlapping the adjacent end of pipe section 615. A member 617 is mounted on pipe section 615 spaced from the end 615a of the pipe section and supports therein a seal 618 in the form of a piston ring for slidingly engaging with the internal wall portion of pipe 614 for longitudinal movement of pipe 615 into and out of pipe 614.

The thermal reactor has a reaction zone indicated by reference letter R extending along a section of pipe 611, it being understood that the length of this reaction zone can be readily increased by including therein a portion of elbow 610. The reaction zone R is formed by the external sleeve 612, the internal pipe section 614, with the cavity defined between the external sleeve and the internal pipe section being filled with insulation 619. This insulation is as discussed relative to the previous embodiments, it being understood that the same type or types of insulation are intended for use herein. An angular abutment 621 is rigidly connected to the external sleeve 612 and the elbow 610 at their mutually adjacent edges, the abutment 621 supporting thereon a disc 620 which in turn holds the internal pipe section 614a in position. The metallic contact area between disc 620 and angular abutment 621 is substantially only a line type contact so that a minimum amount of heat transfer takes place between the disc and abutment. In other words, a minimal heat transfer therefore takes place between the internal pipe 613 and external sleeve 612. As seen in FIG. 17, the support disc 620 and abutment 621 only cover a portion of the total circumference with the cavity holding the insulation 619 being restricted on one side by support disc 620 and on the opposite side by a ring 622 which is rigidly connected to the external sleeve 612. The direction of gas flow through the pipes is indicated by the reference letter S such that support disc 620 is on the gas entry side of the reaction zone R with ring 622 being positioned at the terminal portion of the reaction zone.

As seen in FIG. 15, the internal pipe section 614 is provided with an enlarged diameter in the area of the reaction zone R to reduce the speed of the gas therethrough in order to keep the gas in the hot reaction zone for a longer period of time to assure complete combustion thereof.

Immediately following the reaction zone R is a cooling zone K through which the exhaust gases flow and are cooled to a reduced temperature prior to discharge from the thermal reactor. The external sleeve 612 is provided with port 623 positioned in the external sleeve at the entrance to the cooling zone K of pipe section 614. The ports have associated therewith a plurality of vanes 624 for directing cooling air in the direction of arrow X therethroughinto the inner portions of the external sleeve wherein annulus chamber 625 is defined between external sleeve 612 and internal pipe 613.1t is to be appreciated that when the present invention is applied to a vehicle, when directed by the vanes is guided in the direction of arrow X into the annulus chamber 625 and against the internal pipe 613 subjecting the same to a cooling effect which is high enough to cool the exhaust gases within the cooling zone K.

The sliding point of contact between seal 618 and pipe end 614C, indicated by point G, is thus subjected to an intensive cooling effect since point G is located a substantial distance away from the reaction zone R. Further, as the gap 626 between the end of pipe 615 and the internal wall surface of the adjacent end of pipe 613 is maintained at a minimum, only cooled gases pass through the sliding point G.

The cooling air, after flowing through the annulus chamber 625 exists therefrom in the rearward area of the cooling zone K by being discharged to the atmosphere through ports 627 and 628 disposed in external sleeve 612, such discharge taking place after the cooled air has cooled the sliding point G.

The rearward portion of the external sleeve 612 is manufactured as a separate element 629 and is welded during assembly to the rearward portion of external sleeve 612. This weld joint may serve as a convenient mounting point for mounting clamp 630 in order to attach the thermal reactor to a part of the vehicle (not shown).

When the internal pipe613 expands by virtue of the high temperatures inside the reaction zone in the area of l,l0OCv to 1,200C, the expansion therein occurs only by a sliding movement of internal pipe section 614 along internal pipe section 615 at sliding point G. In view of the intensive cooling in cooling zone K, the temperature at the sliding point G is reduced several hundred degrees Centigrade over the temperature prevalent in the reaction zone R, thereby substantially extending the useful life of seal 618. Any attempt at shifting within the reaction zone R is prevented by the abutment 621 which supports the internal pipe 614.

Referring to FIGS. 18 and 19, there is illustrated a further embodiment of the invention which, while similar to the embodiment of FIGS. 15-17, differs therefrom as to the type of elbow structure connecting the reactor to the engine housing, along with other structural differences including the elimination of the sliding contact between the internal pipe sections. In this form of the invention, reference numeral 711 generally indicates a pipe system which includes an elbow 710, an external sleeve 712, and an internal pipe 713, which internal pipe 713 includes internal pipe sections 714 and 715. The gas flow through the pipe system is indicated by the direction of arrow S. The elbow 710 contains therein two separate branch pipes 733 and 734 around which is arranged external sleeve 731 with insulation 732 filling the cavity defined between the external sleeve and the branch pipes. An end 7330 of branch pipe 733 is inserted into a center bore of a flange 735 and welded thereto in an airtight manner, with an adjacent end 734a of branch pipe 734 being similarly inserted and welded to a center bore of a flange 736. Flanges 735, 736 are adapted for rigid mounting to an engine housing of an internal combustion engine (not shown). One end of external sleeve 731 is attached and welded to the flanges 735, 736, with the opposite end of the external sleeve terminating co-planar with the opposite ends of branch pipes 733, 734 with the branch pipes contacting the external sleeve only along a lineof-contact indicated by reference numeral 737.

The internal pipe section 714 is held in position by a support disc 720 mounted at the end of the pipe section adjacent the elbow 710, the disc 720 being supported on an angular abutment 721 which is rigidly connected to the adjacent end of the elbow. As in the embodiment of FIGS. 15-17, the metallic contact area of disc 720 to abutment 721 is substantially a line type contact so that a minimum heat transfer takes place between internal pipes 714, 733, 734 and external sleeves 712, 73 l.

As to the contact point 737 between internal branch pipes 733, 734 and external sleeve 731, it is to be appreciated that such contact point is spaced a distance from the flanges 735, 736 equal to a multiple of the pipe diameters of the branch pipes which are selected depending upon the intended usage for the invention. The branch pipes 733, 734 terminate at contact point 737 and are united into a single enlarged internal pipe section 714. As the elbow 710 forms a part of the reaction zone (that zone indicated by reference letter R in FIG. 15), the internal branch pipes 733, 734 form a freely expanding and flexing type yoke which is on one end rigidly connected to the engine housing by flanges 735, 736 and on the other end combined at contact point 737 into a single internal pipe section 714. Forces and stresses on the internal branch pipe 733, 734 caused by different heat expansion of the internal pipes or external sleeve 731 therefore do not lead to high stresses or cracks in the pipe system in view of this freely expanding and flexing yoke structure providing appropriate yield characteristics for the pipes.

As previously indicated, the internal pipe 713 is subdivided into internal pipe sections 714 and 715 in a manner similar to the embodiment of FIGS. 15-17. However, differing from said embodiment the sliding contact point of the present invention, indicated by reference letter G1, is located in the terminal portion of the hot reaction zone R which is surrounded by insulation 719 filling the cavity defined by internal pipe 713 and external sleeve 712.

The end ofinternal pipe section 714 opposite the end attached to elbow 710 is provided with two concentric pipe walls 738, 739 weldedly attached to each other at their inwardly most ends to create an annular chamber 740 therebetween. An adjacent end 715a of pipe section 715 is slidably received between pipe walls 738, 739 and protrudes into annular chamber 740 with minimum circumferential radial clearances 741, 742 between the pipe walls and the end of pipe section 715 so that a labyrinth-like seal is created. An annular cavity 725 is defined between pipe section 715 and external sleeve 712, the end of annular chamber 725 adjacent insulation 719 being partially separated from the insulation by an annular disc 744 leaving a slight area 743 for communication between the insulation 719 and annular chamber 715. The opposite end of chamber 725 is sealed in airtight manner to pipe section 715.

in view of this sliding joint connection between pipes 714 and 715, the exhaust gases flowing in direction of arrow 5 through these pipes can only enter the joint clearance 742 by reversing flow direction as seen arrows s1, after which the gases must again reverse flow direction in the annular cavity 740 prior to passing through clearance 741 and entering into annular chamber 725. In this manner insulation 719 is not strained by pulsating gases in annular chamber 725 so that the insulation is protected against premature destruction.

The volume of gas in annular chamber 725 may be considered an equalization volume as the gases are contained therein in an almost stationary condition. Simultaneously, annular chamber 725 also protects the external sleeve 712 against the high temperatures of internal pipe 715.

It is to be understood that the forms of the invention herewith shown and described are to be taken as preferred embodiments of the same, and that other forms and embodiments of the thermal reactor are possible in a manner in accord with the invention so that various changes in the shape, size, and arrangement of parts may be resorted to without departing from the spirit of the invention or the scope of the subjoined claims.

What is claimed is:

1. A thermal reactor having an entrance and a discharge end for use with exhaust systems of internal combustion engines comprising:

an internal pipe divided into a plurality of separate sections in communication with each other B1 and disposed adjacently to each other along the longitudinal axis of the reactor;

joint means interconnecting two of said internal pipe sections;

an external tubular sleeve surrounding at least one of said separate sections of said internal pipe and radially spaced therefrom to form an annular cavity therebetween, the ends of said external sleeve being connected in an air-tight manner to said internal pipe;

insulating material inserted in a portion of the annular cavity between said external sleeve and said internal pipe section, the portion of the reactor so insulated defining a reaction zone; and

a pressure equalization chamber disposed adjacent and rearwardly of said reaction zone and defined by that portion of the annular cavity between said external sleeve and said internal pipe section in which no insulation is present, said pressure equalization chamber being in flow communication with said internal pipe by way of said joint means.

2. A thermal reactor as claimed in claim 1 wherein adjacent ends of adjacent pipe sections and slidingly joined together to form a joint permitting relative overlapping movement therebetween to accommodate expansion of the internal pipe sections, the end of each pipe section being slidingly received and supported in the adjacent end of the adjacent pipe section.

3. The thermal reactor as claimed in claim 2 wherein the exit end of at least one of said pipe sections has concentric wall portions forming an annular recess therebetween, the entrance end of an adjacent pipe section being slidably received in the annular recess with minimum axial gap formed between the entrance end and the end of the annular recess to form a labyrinth type joint between the entrance end and the exit end of the adjacent joined internal pipe sections.

4. The thermal reactor as claimed in claim 3 wherein the entrance end is received in the annular recess of the adjacent exit end and radially spaced a minimum distance from the concentric portions forming a pocket shaped cavity with the axial gap located between the entrance and exit ends.

5. The thermal reactor as claimed in claim 2 wherein the internal pipe section located within the reaction zone extends outwardly from the reaction zone toward the discharge end of the reactor, and the entrance end of the adjacent pipe section slidingly received and supported in the exit end of the pipe section in the reaction zone with the sliding contact therebetween located at the discharge end of the reaction zone.

6. The thermal reactor as claimed in claim 5 wherein the sliding connection between the exit end and entrance end permits the loss of a slight amount of gas from the connection as the gas passes therebetween.

7. The thermal reactor as claimed in claim 5 wherein the internal pipe has an expanded diameter in the area forming the reaction zone with respect to the diameter of said entrance end so as to slow the flow of gas therethrough.

8. The thermal reactor as claimed in claim 5 wherein the exit end of the pipe section has concentric wall portions forming an annular recess therebetween, the entrance end of the adjacent pipe section being slidably received in the annular recess with slight axial and radial gap clearance between the exit and entrance ends.

9. The thermal reactor as clained in claim 8 wherein the axial and radial gaps formed between the entrance end and the walls of the annular recess form a labyrinth-type joint therebetween so as to require that gases to penetrate the joint must first reverse flow direction to enter the annular recess, and then again reverse direction of flow to exit from the annular recess.

10. The thermal reactor as claimed in claim 5 further comprising a pipe located forwardly of the internal pipe reaction zone, the forward pipe being subdivided into a plurality of branch pipes, the entry end of each branch pipe adapted for mounting to an exhaust from a cylinder of an internal combustion engine, an external ,sleeve spaced from and surrounding the branch pipes having one end mounted to the housing of the engine, the length of each branch pipe being a selected multiple of its diameter, and the discharge end of each branch pipe combining at a common connecting point prior to the entrance end of the internal pipe to equalize the different expansions of the branch pipes occurring during the heating of the same.

11. The thermal reactor as claimed in claim 5 further comprising a forward pipe section located forwardly of the internal pipe, the pipe section being subdivided with each section discharging into the internal pipe, an abutment mounted of the exit end of the forward pipe section, a second abutment mounted on the entrance end of the internal pipe adapted to engage the first abutment and support the entrance end of the internal pipe in an axial direction thereon, whereby in a heated condition the internal pipe may axially expand at the sliding connection in the direction of the flow of gases.

12. The thermal reactor as claimed in claim 11 wherein the first and second abutments have a minimum line-of-contact therebetween providing the minimal heat transfer between the internal pipe and external sleeve.

13. A thermal reactor having an entrance and a discharge end for use with exhaust systems of internal combustion engines comprising an internal pipe divided into a plurality of separate sections in communication with each other, an external tubular sleeve surrounding at least one of said separate sections of said internal pipe and radially spaced therefrom to form an annular cavity therebetween, the ends of said external sleeve being connected in an air-tight manner to said internal pipe, insulating material inserted in the annular cavity between said external sleeve and said internal pipe section, the adjacent ends of adjacent pipe sections being slidingly joined together to form ajoint permitting relative overlapping movement therebetween, the end of each pipe section being slidingly received and supported in the adjacent end of the adjacent pipe section, a reaction zone defined by the portion of the internal pipe having the insulating material therearound, the internal pipe extending outwardly from the reaction zone toward the discharge end of the reactor, the internal pipe having a pipe section located in the reaction zone, and the entrance end of the adjacent pipe section slidingly received and supported in the exit end of the pipe section in the reaction zone with the sliding contact therebetween located at the discharge end of the reaction zone, the exit end of the pipe section having concentric wall portions forming an annular recess therebetween, the entrance end of the adjacent pipe section being slidably received in the annular recess with slight axial and radial gap clearance between the exit and entrance ends, the axial and radial gaps formed between the entrance end and the walls of the annular recess forming a labyrinth-type joint therebetween so as to require that gases to penetratethe joint must first reverse flow direction to enter the annular recess, and then again reverse direction of flow to exit from the annular recess, and a chamber disposed rearwardly of the reaction zone between the internal pipe and external sleeve, the chamber being sealed to the atmosphere with the gases exiting from the annular recess directly into the chamber.

14. The thermal reactor as claimed in claim 13 wherein the chamber is in partial communication with the insulating material located in the area of the reaction zone.

15. A thermal reactor having an entrance and a discharge end for use with exhaust systems of internal combustion engines comprising an internal pipe divided into a plurality of separate sections in communication with each other, an external tubular sleeve sur' rounding at least one of said separate sections of said internal pipe and radially spaced therefrom to form an annular cavity therebetween, the ends of said external sleeve being connected in an air-tight manner to said internal pipe, insulating material inserted in the annular cavity between said external sleeve and said internal pipe section, the adjacent ends of adjacent pipe sections being slidingly joined together to form a joint permitting relative overlapping movement therebetween, the end of each pipe section being slidingly received and supported in the adjacent end of the adjacent pipe section, the exit end of at least one of said pipe sections having concentric wall portions forming an annular recess therebetween, the entrance end of an adjacent pipe section being slidably received in the annular recess with minimum axial gap formed between the entrance end and the end of the annular recess to form a labyrinth type joint between the entrance end and the exit end of the adjacent joined internal pipe sections, the entrance end being received in the annular recess of the adjacent exit end and radially spaced a minimum distance from the concentric portions forming a pocket shaped cavity with the axial gap located between the entrance and exit ends, and a pressure equalization chamber defined between a portion of the internal pipe and a portion of the external sleeve, the radial spacing between the outermost wall surface of the entrance end and the innermost wall surface of the outermost concentric wall discharging into the pressure equalization chamber.

16. The thermal reactor as claimed in claim 15 wherein the pressure equalization chamber is located at the discharge end portion of the reactor immediately rearwardly of the end of the insulation material in the annular cavity.

17. A thermal reactor having an entrance and a discharge end for use with exhaust systems of internal combustion engines comprising an internal pipe divided into a plurality of separate sections in communication with each other, an external tubular sleeve surrounding at least one of said separate sections of said internal pipe and radially spaced therefrom to form an annular cavity therebetween, the ends of said external sleeve being connected in an air-tight manner to said internal pipe, insulating material inserted in the annular cavity between said external sleeve and said internal pipe section, the adjacent ends of adjacent pipe sections being slidingly joined together to form a joint permitting relative overlapping movement therebetween, the end of each pipe section being slidingly received and supported in the adjacent end of the adjacent pipe section, a reaction zone defined by the portion of the internal pipe having the insulating material therearound, the internal pipe extending outwardly from the reaction zone toward the discharge end of the reactor, the internal pipe having a pipe section located in the reaction zone, and the entrance end of the adjacent pipe section slidingly received and supported in the exit end of the pipe section in the reaction zone with the sliding contact therebetween located at the discharge end of the reaction zone, a forward pipe section located forwardly of the internal pipe, the pipe section being subdivided with each section discharging into the internal pipe, a first abutment mounted on the exit end of the forward pipe section, a second abutment mounted on the entrance end of the internal pipe adapted to engage the first abutment and support the entrance end of the internal pipe in an axial direction thereon, whereby in a heated condition the internal pipe may axially expand at the sliding connection in the direction of the flow of gases, and the first and second abutments covering only the upper portion of the circumference of the internal pipe and external sleeve. 

1. A thermal reactor having an entrance and a discharge end for use with exhaust systems of internal combustion engines comprising: an internal pipe divided into a plurality of separate sections in communication with each other B1 and disposed adjacently to each other along the longitudinal axis of the reactor; joint means interconnecting two of said internal pipe sections; an external tubular sleeve surrounding at least one of said separate sections of said internal pipe and radially spaced therefrom to form an annular cavity therebetween, the ends of said external sleeve being connected in an air-tight manner to said internal pipe; insulating material inserted in a portion of the annular cavity between said external sleeve and said internal pipe section, the portion of the reactor so insulated defining a reaction zone; and a pressure equalization chamber disposed adjacent and rearwardly of said reaction zone and defined by that portion of the annular cavity between said external sleeve and said internal pipe section in which no insulation is present, said pressure equalization chamber being in flow communication with said internal pipe by way of said joint means.
 2. A thermal reactor as claimed in claim 1 wherein adjacent ends of adjacent pipe sections and slidingly joined together to form a joint permitting relative overlapping movement therebetween to accommodate expansion of the internal pipe sections, the end of each pipe section being slidingly received and supported in the adjacent end of the adjacent pipe section.
 3. The thermal reactor as claimed in claim 2 wherein the exit end of at least one of said pipe sections has concentric wall portions forming an annular recess therebetween, the entrance end of an adjacent pipe section being slidably received in the annular recess with minimum axial gap formed between the entrance end and the end of the annular recess to form a labyrinth type joint between the entrance end and the exit end of the adjacent joined internal pipe sections.
 4. The thermal reactor as claimed in claim 3 wherein the entrance end is received in the annular recess of the adjacent exit end and radially spaced a minimum distance from the concentric portions forming a pocket shaped cavity with the axial gap located between the entrance and exit ends.
 5. The thermal reactor as claimed in claim 2 wherein the internal pipe section located within the reaction zone extends outwardly from the reaction zone toward the discharge end of the reactor, and the entrance end of the adjacent pipe section slidingly received and supported in the exit end of the pipe section in the reaction zone with the sliding contact therebetween located at the discharge end of the reaction zone.
 6. The thermal reactor as claimed in claim 5 wherein the sliding connection between the exit end and entrance end permits the loss of a slight amount of gas from the connection as the gas passes therebetween.
 7. The thermal reactor as claimed in claim 5 wherein the internal pipe has an expanded diameter in the area forming the reaction zone with resPect to the diameter of said entrance end so as to slow the flow of gas therethrough.
 8. The thermal reactor as claimed in claim 5 wherein the exit end of the pipe section has concentric wall portions forming an annular recess therebetween, the entrance end of the adjacent pipe section being slidably received in the annular recess with slight axial and radial gap clearance between the exit and entrance ends.
 9. The thermal reactor as clained in claim 8 wherein the axial and radial gaps formed between the entrance end and the walls of the annular recess form a labyrinth-type joint therebetween so as to require that gases to penetrate the joint must first reverse flow direction to enter the annular recess, and then again reverse direction of flow to exit from the annular recess.
 10. The thermal reactor as claimed in claim 5 further comprising a pipe located forwardly of the internal pipe reaction zone, the forward pipe being subdivided into a plurality of branch pipes, the entry end of each branch pipe adapted for mounting to an exhaust from a cylinder of an internal combustion engine, an external sleeve spaced from and surrounding the branch pipes having one end mounted to the housing of the engine, the length of each branch pipe being a selected multiple of its diameter, and the discharge end of each branch pipe combining at a common connecting point prior to the entrance end of the internal pipe to equalize the different expansions of the branch pipes occurring during the heating of the same.
 11. The thermal reactor as claimed in claim 5 further comprising a forward pipe section located forwardly of the internal pipe, the pipe section being subdivided with each section discharging into the internal pipe, an abutment mounted of the exit end of the forward pipe section, a second abutment mounted on the entrance end of the internal pipe adapted to engage the first abutment and support the entrance end of the internal pipe in an axial direction thereon, whereby in a heated condition the internal pipe may axially expand at the sliding connection in the direction of the flow of gases.
 12. The thermal reactor as claimed in claim 11 wherein the first and second abutments have a minimum line-of-contact therebetween providing the minimal heat transfer between the internal pipe and external sleeve.
 13. A thermal reactor having an entrance and a discharge end for use with exhaust systems of internal combustion engines comprising an internal pipe divided into a plurality of separate sections in communication with each other, an external tubular sleeve surrounding at least one of said separate sections of said internal pipe and radially spaced therefrom to form an annular cavity therebetween, the ends of said external sleeve being connected in an air-tight manner to said internal pipe, insulating material inserted in the annular cavity between said external sleeve and said internal pipe section, the adjacent ends of adjacent pipe sections being slidingly joined together to form a joint permitting relative overlapping movement therebetween, the end of each pipe section being slidingly received and supported in the adjacent end of the adjacent pipe section, a reaction zone defined by the portion of the internal pipe having the insulating material therearound, the internal pipe extending outwardly from the reaction zone toward the discharge end of the reactor, the internal pipe having a pipe section located in the reaction zone, and the entrance end of the adjacent pipe section slidingly received and supported in the exit end of the pipe section in the reaction zone with the sliding contact therebetween located at the discharge end of the reaction zone, the exit end of the pipe section having concentric wall portions forming an annular recess therebetween, the entrance end of the adjacent pipe section being slidably received in the annular recess with slight axial and radial gap clearance between the exit and entrance ends, the axial and radial gaps formed between the entrance enD and the walls of the annular recess forming a labyrinth-type joint therebetween so as to require that gases to penetrate the joint must first reverse flow direction to enter the annular recess, and then again reverse direction of flow to exit from the annular recess, and a chamber disposed rearwardly of the reaction zone between the internal pipe and external sleeve, the chamber being sealed to the atmosphere with the gases exiting from the annular recess directly into the chamber.
 14. The thermal reactor as claimed in claim 13 wherein the chamber is in partial communication with the insulating material located in the area of the reaction zone.
 15. A thermal reactor having an entrance and a discharge end for use with exhaust systems of internal combustion engines comprising an internal pipe divided into a plurality of separate sections in communication with each other, an external tubular sleeve surrounding at least one of said separate sections of said internal pipe and radially spaced therefrom to form an annular cavity therebetween, the ends of said external sleeve being connected in an air-tight manner to said internal pipe, insulating material inserted in the annular cavity between said external sleeve and said internal pipe section, the adjacent ends of adjacent pipe sections being slidingly joined together to form a joint permitting relative overlapping movement therebetween, the end of each pipe section being slidingly received and supported in the adjacent end of the adjacent pipe section, the exit end of at least one of said pipe sections having concentric wall portions forming an annular recess therebetween, the entrance end of an adjacent pipe section being slidably received in the annular recess with minimum axial gap formed between the entrance end and the end of the annular recess to form a labyrinth type joint between the entrance end and the exit end of the adjacent joined internal pipe sections, the entrance end being received in the annular recess of the adjacent exit end and radially spaced a minimum distance from the concentric portions forming a pocket shaped cavity with the axial gap located between the entrance and exit ends, and a pressure equalization chamber defined between a portion of the internal pipe and a portion of the external sleeve, the radial spacing between the outermost wall surface of the entrance end and the innermost wall surface of the outermost concentric wall discharging into the pressure equalization chamber.
 16. The thermal reactor as claimed in claim 15 wherein the pressure equalization chamber is located at the discharge end portion of the reactor immediately rearwardly of the end of the insulation material in the annular cavity.
 17. A thermal reactor having an entrance and a discharge end for use with exhaust systems of internal combustion engines comprising an internal pipe divided into a plurality of separate sections in communication with each other, an external tubular sleeve surrounding at least one of said separate sections of said internal pipe and radially spaced therefrom to form an annular cavity therebetween, the ends of said external sleeve being connected in an air-tight manner to said internal pipe, insulating material inserted in the annular cavity between said external sleeve and said internal pipe section, the adjacent ends of adjacent pipe sections being slidingly joined together to form a joint permitting relative overlapping movement therebetween, the end of each pipe section being slidingly received and supported in the adjacent end of the adjacent pipe section, a reaction zone defined by the portion of the internal pipe having the insulating material therearound, the internal pipe extending outwardly from the reaction zone toward the discharge end of the reactor, the internal pipe having a pipe section located in the reaction zone, and the entrance end of the adjacent pipe section slidingly received and supported in the exit end of the pipe section in the reaction zone with the slidiNg contact therebetween located at the discharge end of the reaction zone, a forward pipe section located forwardly of the internal pipe, the pipe section being subdivided with each section discharging into the internal pipe, a first abutment mounted on the exit end of the forward pipe section, a second abutment mounted on the entrance end of the internal pipe adapted to engage the first abutment and support the entrance end of the internal pipe in an axial direction thereon, whereby in a heated condition the internal pipe may axially expand at the sliding connection in the direction of the flow of gases, and the first and second abutments covering only the upper portion of the circumference of the internal pipe and external sleeve. 